Airplanes in Space?

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A British firm is upping the ante in a long-held dream to build
an airplane that also can fly in space.

With support from the U.K. Space Agency, Reaction Engines is
building a prototype of a critical piece of its spaceplane's
technology, which will be tested on a conventional jet engine.

The ultimate goal is Skylon, an unpiloted, air-breathing vehicle
that takes off and lands on a runway, and can travel beyond
Earth's atmosphere.

Rather than using expensive rocket motors that have to be
discarded or refurbished after every flight, Skylon is powered by
two hybrid engines that can use oxygen from the air when
available or liquid oxygen when there is no air. Its propellant
is liquid hydrogen.

"It's the holy grail of aeronautics," said Richard Varvill,
Reaction Engines technical director and a company co-founder.

The company figures a launch would cost about $10 million,
compared to about $150 million for a rocket launch today. Skylon
is being designed to carry cargo and satellites into orbit, but
it can be adapted to fly a pod for passengers as well.

So far, seven private citizens have flown in space aboard Russian
Soyuz capsules at a cost of $25 million to $40 million per seat.
A commercial suborbital spaceship owned by Virgin Galactic is
under development, with service expected to begin in late 2011 or
2012. Tickets for suborbital rides, which will put people above
the atmosphere for about five minutes, sell for $200,000.

"If you're able to access space cheaply and safely, there are a
lot of applications that will flow back. But at the moment, it's
completely impractical," Varvill told Discovery News.

Reaction Engines is focusing on a critical piece of technology
called a heat exchanger, needed to rapidly cool the air before it
can be used by the spaceplane's engines.

"It allows the air to be compressed to higher pressures than what
has been done previously," Varvill told Discovery News.

"They've already built subscale pieces and tested it in the lab,
so now they're moving on to a demonstration at a very large
scale. The key is making it light enough to be on an engine,"
added Dave Parker, director of space science and exploration at
the U.K. Space Agency.

The project is far enough along that last month the British space
agency hosted a workshop to introduce Skylon to engineers and
managers from the United States, Japan, Russia, Europe and
elsewhere.

Skylon's founders were part of a British Aerospace-Rolls Royce
spaceplane project in the 1980s called HOTOL -- short for
Horizontal Take Off and Landing, which was to be completely
reusable.

"These are not people who started this last week," Parker told
Discovery News. "They've been gnawing away at the problem for 20
years now. These are serious engineers."